Two-way serial communications in electrical systems are accomplished, in part, with electrical interfaces between nodes. For example, a controller area network or carrier area-wide network (both hereinafter referred to as “CAN”) provides two-way serial communications via electrically-conductive wire according to CAN standard ISO 11898-2. The communications are provided between CAN transmitter receiver nodes. Electrical interfaces, such as repeaters and/or terminators, are provided between the nodes to match impedance and provide operating voltage levels that comply with the CAN standard.
In some applications, the nodes may be electrically connected by long cabling runs that may be up to 1 kilometer or so long. As a result, signals are driven by a driver in order to overcome losses over long distances. In this event, active repeater/terminators are provided to receive signals, buffer the signals, and transmit the signals.
Active repeater/terminators provide good drive over long distances. However, active repeater/terminators include relatively complex, active electronic circuitry. The active circuitry of one commercially-available active repeater/terminator requires external power and is galvanically isolated between channels. A level of active arbitration is required for mitigation of data path selection, thereby adding further complexity to the active repeater/terminator. Another commercially-available active repeater/terminator uses an optical coupler and provides optical isolation. However, drive capability is limited and external power is required. Both of these commercially-available active repeater/terminators have a relatively large size, generate heat, and consume processing resources. As a result, both of these active repeater/terminators are complex, suffer from reliability concerns, and are relatively expensive.
In other applications, it may be desirable to transmit a signal to multiple destinations and receive data back from the multiple destinations. Some of these applications may entail short signal paths. Therefore, it is not necessary to actively drive signals between nodes. It would be desirable to provide repeater/terminators that do not entail external power supplies, complexity, costs, reliability, and other concerns of active repeater/terminators. However, there is an unmet need in the art for a passive repeater/terminator.